1. Field of the Invention
The present invention relates to the field of editing data of sequences of images, e.g. video, in particular, the transition between a first source sequence of images to a second source sequence of images.
2. Description of the Related Art
It is well known in the art that a static image, e.g. a photograph, can be converted into a digital representation of the static image. Similarly, it is well known in the art to convert dynamic images, i.e., video images, into a digital representation. Typically, in the digital representation on, for example, a computer system, the video image is captured as a sequence of static images. Each static image captures an instant in time of the video image. Movement is apparent to the viewer by the rapid display of the sequence of static images.
It is often the case where a first collection of video images is contiguously merged with or transitioned into, a second collection of video images. The mechanics of such a merging or transitioning of video images is described in more detail below in conjunction with specifically designed devices which perform this function. Common techniques known in the art that are used for creating a transition from one video image to a second video image are called "switches". Such "switches" include cuts, wipes, irises, fades and pushes. It should be noted that switching is used in the context of live television broadcasts; where, for example, during a newscast, when a switch is made from a newsperson reporting the weather to a newsperson reporting sports.
As described above, a video image in its digital representation is typically a sequence of static images. It is these sequences of static images which are combined to create a transition. A cut switch is illustrated in FIG. 1a. A first sequence of images is represented by 101 and a second sequence of images is represented by 102. A cut switch results in the sequence of images represented by 103. The sequence of images 103 is what a viewer of the images would see. Here, the sequence of images represented by 101 are sequentially contiguous with the sequence of images represented by 102. In a cut switch there is no overlapping of the two sequences of images. The transition effect is to abruptly change from a scene in the first sequence of images to a scene in the second sequence of images.
A wipe switch is illustrated in FIG. 1b. Here, the second sequence of images 102 overlays the first sequence of images 101, creating an overlay sequence of images represented by 105. The amount of overlap will increase over time, creating a gradual transition effect from the first sequence of images 101 to the second sequence of images 102. The transition effect is to wipe the images of the first sequence with the images of the second sequence. It is known in the art that the wipe switch may come from any direction, e.g. left to fight, right to left, top to bottom or bottom to top.
An iris switch is illustrated in FIG. 1c. Here the first sequence of images 101 is seemingly taken over by the second sequence of images 102. The iris is used in the optical sense, as an opening up to obtain more light. In the sequence of images represented by 102 the second sequence of images 102 is displayed in the middle of the first sequence of images 101, illustrated as 108. Over time, the portion displaying the second sequence of images 102 expands until only the second sequence of images is displayed. The transition effect is the opening of an iris to display the second sequence of images. The initial opening of the iris switch may originate from any point on the display of the images.
A push switch is illustrated in FIG. 1d. Here the first sequence of images 101 is pushed out of view by the second sequence of images 102. In this example, the right most portion of the second sequence of images 102 appears to be pushing the left most portion of the first sequence of images 101, as illustrated in the sequence represented by 109. This occurs over time until the second sequence of images 102 is fully displayed. The transition effect is of the second sequence of images physically pushing the first sequence of images out of view (or off the screen). However, the push direction may alternatively be fight to left, top to bottom or bottom to top.
A fade switch is illustrated in FIG. 1e. Here, the first sequence of images 101 gradually fades to a predetermined color, e.g. black. As illustrated in the sequence represented by 110, a first static image 111 which is gray, is followed by an image 112 which is black. The sequence of images 110 will then continue with a gray image 113 until the second sequence of images 102 is displayed. The transition effect is to fade the first sequence of images to a predetermined color and then to immediately fade from the predetermined color to the second sequence of images.
A dissolve switch (not illustrated) is conceptually identical to a fade switch, except that the first sequence of images transitions directly into the second sequence of images rather than to an intermediate predetermined color.
Means for creating a transition effect or switch are known in the art. Such means include individually creating the static images for the switch from which the first and second image sequences are combined, and interpolation. Interpolation refers to creating a begin and end state for a transition and utilizing a processing means to determine the transition states in between. Known tools for creating a switch or transition effect that exist in the art are limited in that they perform only a specific effect or a set of pre-defined effects. Since the sequence of images is in a digital representation it would be useful to use a general purpose computer system to manipulate the data to create a transition between the sequence of images.
A step in this direction is found in a commercially available product known as the Video Toaster, manufactured and sold by NewTek, Inc. of Topeka Kansas. The Video Toaster includes specifically designed video graphics chips and is designed to be used with a computer system known as the AMIGA System, available from Commodore Business Machines, Inc., of Westchester, Pa. The Video Toaster provides predefined switches, fading and other video editing capabilities. Additionally, the Video Toaster requires the use of at least two display devices. A first display device provides for a user interface to the video editing tools, while a second display device displays the program image.
The Video Toaster provides a user interface that is typical for switching devices. A user interface is the means by which a user interacts with a computer system or other device. Such a typical user interface for switching devices is as illustrated in FIG. 2. A first row of identifiers 201 provides for selection of a first input source, typically called a program source, a second row of identifiers 202 provides for selection of a second input source typically called a preview source, a manual T-Bar switcher 203 provides for switching from a program source to a preview source and a take button 204, provides for initiating a pre-defined switch. The identifiers in row 201 and 202 are typically push buttons which illuminate when that source is selected. In FIG. 2, the button 205 representing program source 2 and the button 206 representing the preview source 4 are illuminated and thus selected. The buttons which are selected determine the sequence of images which will include a switch.
The video source represented by each of the identifiers are from independent video sources, e.g. a camera or VCR. Additionally, there may be a dedicated monitor for displaying the program source. The source itself would generally be viewable via a display such as a television or monitor. So in reference to FIG. 2 a source may be either a program or preview source. During a switch, the program source will transition to the preview source. A user may verify the switch in two ways. First, the monitor displaying the program source would now be displaying the new program (previously the preview) source. Additionally, the identifier representing the new program source would be illuminated (and the previous program source would not). In the interface the identifier representing the program source and the preview source, will be illuminated.
A cut switch as described above may be performed by depressing a button in the program row of the desired program source. A fade switch will occur by using the T-Bar switcher 203. This may typically happen by pulling the handle of the T-Bar switcher downward. In this way, the speed of the fade may be controlled. In some switch devices the switch itself defines the manner in which the switch will occur. With the aforementioned Video Toaster, the switch type may be chosen from a plurality of icons presented to the user. The user would typically position the cursor over the desired icon with a cursor control device, such as a mouse or track-ball, and click on the icon. Clicking refers to rapidly depressing and releasing a button (i.e. an electrical switch) associated with the cursor control device. By depressing the take or auto button, the switch would take place according to the selected switch effect.
The video switch interface described above is known to those skilled in the art of video switching. However, it is believed that this video switching interface is not well known to the average computer system user. As the use of video in computer systems is increasingly being used to convey information, a higher number of people will be required to perform video editing like functions. It would be desirable to provide a user interface to such a video switching system that is consistent with known user interfaces, e.g. the Macintosh.RTM. interface, of the Macintosh family of computers (available from Apple Computer, Inc. of Cupertino, Calif.).
Further, a user of the Video Toaster and other known switching devices selects a transition effect by choosing a static icon representing the effect. It would be beneficial to provide a system where a transition effect can be chosen by a user in a What You See Is What You Get (WYSIWYG) fashion. WYSIWYG is a term that refers to a user interface. A WYSIWYG user interface allows for a user to visually see the effect of a performed operation. This allows the user to make more informed choices about alternative video effects. Although a static icon is useful when representing application software or a data file, it does not provide the user with the dynamic visualization needed to truly determine what the effect will be. WYSIWYG in this context also refers to the capability to view both the first source sequence of images and the second source sequence of images on the same display.
It is also significant that in the known prior art, no means are provided for a user to create a switch. The user is limited to the types of switches that are provided where each switch displays predetermined sequences of images which are displayed by selecting a particular button, such as button 205 or 206. As described above, the use of video in computer systems is emerging as a means of providing information. Thus, it is beneficial to the creator of that information to have the means to customize a switch to meet their particular needs.
It is an object of the present invention to provide a system where transition effects are presented in a WYSIWYG fashion and that provides a means for user definition and tailoring of a transition effect.